24-Hour IOP Monitoring: Emerging Home and Implantable Technologies

Glaucoma management is poised for a transformation as novel 24-hour intraocular pressure (IOP) monitoring tools come into practice. Traditional office IOP checks miss the nocturnal and early-morning spikes that many patients experience (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). In 2025, home-accessible rebound tonometers, contact-lens sensors, and implantable telemetric devices are beginning to fill this gap. These technologies capture diurnal and nocturnal IOP patterns that were previously unmeasurable, allowing clinicians to detect hidden pressure peaks and tailor treatment more precisely. This article reviews the evidence behind these devices, patient adherence and data quality, and how out-of-office IOP data are now influencing medical and surgical decision-making (including the timing of MIGS and medication changes). We also discuss the health-economic implications and offer practical advice on selecting patients for home monitoring and implementing remote IOP protocols.

Home Rebound Tonometry

Portable rebound tonometers (e.g. iCare HOME and iCare HOME2) enable patients to measure their own IOP without drops. Studies show these devices are generally reliable when patients are trained. In a large prospective trial, 65% of patients achieved the target of ≥6 measurements per day during a 1–2 week period, with a median of 7.4 readings/day (pmc.ncbi.nlm.nih.gov). However, about 19% of patients recorded very few readings (<2/day); these often cited difficulty in obtaining measurements and a desire for more instruction (pmc.ncbi.nlm.nih.gov). This underscores that training and practice are critical: most protocols involve a one-on-one in-office training session (30–45 minutes) before home use (pmc.ncbi.nlm.nih.gov). Patients who learn proper technique and are motivated generally find these devices easy to use, reporting high satisfaction in small trials.

Once in use, home rebound tonometers reveal rich IOP data. The Cleveland Clinic study noted significant diurnal fluctuation: mean IOP peaked around 3 AM and fell to its lowest near 10 PM (p<0.0001) (pmc.ncbi.nlm.nih.gov). Crucially, 36% of patients had their highest IOP outside of normal clinic hours (pmc.ncbi.nlm.nih.gov). In other words, over a third of patients had hidden pressure spikes that office tonometry would miss. Another review noted that home devices consistently capture higher peak IOPs than office measures, especially at night (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). In practice, this means home tonometry often identifies occult nyctohemeral variability – for example, revealing large overnight spikes or early-morning surges that go unrecognized in daytime exams (pmc.ncbi.nlm.nih.gov) (www.ophthalmologymanagement.com).

Data accuracy is generally good but not perfect. Studies find strong correlation between patient-taken and clinician-taken rebound readings (r≈0.90) (pmc.ncbi.nlm.nih.gov), and many patients (over 75% in one report) can obtain home IOPs comparable to Goldmann applanation values (pmc.ncbi.nlm.nih.gov). Still, agreement is not ideal: one study found only 37% of eyes had simultaneous IOP peaks on home vs. clinic diaries (pmc.ncbi.nlm.nih.gov). Thus, home readings should be interpreted as trends rather than exact replacements for in-office tonometry. Frequent sampling gives a more complete picture of each patient’s IOP curve, even if individual values differ.

Adherence is mixed. While most motivated patients do well, some have trouble. In a pilot of pediatric glaucoma, 28 of 29 children successfully used a handheld rebound monitor twice daily (pmc.ncbi.nlm.nih.gov). In contrast, a U.S. adult study found only 60% of participants could complete a multi-day home-monitoring protocol without supervision (pmc.ncbi.nlm.nih.gov). In that study, 40% of patients struggled with self-tonometry (pmc.ncbi.nlm.nih.gov) (e.g. due to dexterity, comfort or attention issues). Accordingly, patient selection is key: successful users tend to be those who are motivated, have good vision or caregiver help, and no severe hand tremor. Providing clear instructions, follow-up support (videos, hotlines, patient ambassadors), and reinforcement can improve compliance (pmc.ncbi.nlm.nih.gov) (www.ophthalmologymanagement.com).

Modern devices ease data handling. The iCare HOME2 (second-generation) connects via Bluetooth to a smartphone, uploading IOP readings in real time to a secured cloud portal. Clinicians and patients can view plots of daily pressures immediately (www.ophthalmologymanagement.com) (glaucomatoday.com). This feedback loop makes home tonometry part of a telehealth model: clinicians set target IOP thresholds, and automated alerts can flag when a patient’s readings exceed them (glaucomatoday.com). For example, Eyemate (see below) transmits thousands of IOP points to a dashboard integrated with electronic health records (glaucomatoday.com), enabling thorough remote review.

Contact-Lens IOP Sensors

Telemetric contact lenses are another ambulatory option. These are soft lenses with embedded sensors that record corneal strain (from which IOP changes are inferred) continuously over 24 hours. The only commercial device available is the SENSIMED Triggerfish® lens. In clinical trials, wearing this lens for 24 h was generally safe and tolerable. In one study of 40 glaucoma suspects, main adverse events were blurred vision (~82% of patients) and conjunctival redness (~80%) (pubmed.ncbi.nlm.nih.gov), reflecting normal lens discomfort. Patients rated overall lens wear as mild-to-moderate in intensity (mean visual analog score ~25/100) (pubmed.ncbi.nlm.nih.gov). Importantly, no new ocular complications (e.g. infection, corneal ulcer) were seen with its repeated use over a week.

The key output of a contact-lens sensor is a 24-hour IOP profile (in arbitrary units). The data can highlight relative changes and rhythms: for example, one trial found a positive positive slope of the signal from daytime to sleep in untreated eyes (pubmed.ncbi.nlm.nih.gov), consistent with IOP rising overnight. On repeat testing one week apart, the lens’s IOP waveforms showed reasonable reproducibility (overall correlation r≈0.59) (pubmed.ncbi.nlm.nih.gov). In practical terms, a doctor can see when the patient’s pressure tends to climb (e.g. late evening) and use that pattern in decision-making.

Because contact-lens sensors do not report mmHg, clinicians interpret their traces qualitatively. The graphs reveal the timing and relative magnitude of fluctuations. For example, if two patients have very different curve shapes, the one with sharper peaks might be considered at higher risk. Several small studies have shown these patterns carry value: home 24h lens monitoring uncovered nocturnal IOP trends not seen in clinic, sometimes prompting treatment adjustments.

That said, the current CLS designs have downsides. Patients often report discomfort from lens insertion and wear (foreign-body sensation, eye dryness) (pmc.ncbi.nlm.nih.gov). The rigid electronics in the first-generation Triggerfish can feel bulky, and overnight sleep wears it okay but not optimally. These challenges have driven new research. A recent Nature Communications paper described “smart soft contact lenses”: ultrathin, stretchable sensors bonded onto commercial soft lenses (pmc.ncbi.nlm.nih.gov). These prototypes preserve normal lens comfort, biocompatibility and oxygen permeability, yet embed microscopic IOP sensors that output absolute pressure in mmHg (not just relative signals) under ambulation and even during sleep (pmc.ncbi.nlm.nih.gov). In animal tests and a few humans, these new lenses matched standard tonometry across corneal curvatures (pmc.ncbi.nlm.nih.gov). While clinical use is years away, this suggests future contact lenses could become a continuous, wireless IOP monitor akin to a Holter for the eye.

Implantable Telemetry Systems

For truly continuous, high-fidelity monitoring, implantable IOP sensors have been developed. These tiny devices (often CE-marked Eyemate or Argos sensors) are inserted into the eye during surgery and remain permanently. For example, Implandata’s Eyemate-IO is placed in the ciliary sulcus at the time of cataract extraction, while an Eyemate-SC sensor is placed in the suprachoroidal space during glaucoma surgery (glaucomatoday.com). Each implant contains capacitive pressure transducers calibrated in mmHg, and it wirelessly transmits IOP overnight or on demand.

The safety and longevity of these implants have been demonstrated. In the “ARGOS-01” study, six patients had an Eyemate-like sulcus sensor implanted (at cataract surgery). These patients collected IOP readings over many years – in total nearly 25,000 measurements were gathered up to 10 years post-op (pubmed.ncbi.nlm.nih.gov). They reported no chronic discomfort or sensor-related problems during this decade of follow-up (pubmed.ncbi.nlm.nih.gov). The technology was very well tolerated: one patient used a reading device nightly and had no restrictions on daily activities due to the implant (pubmed.ncbi.nlm.nih.gov). A 2018 follow-up study (mean 3 years) similarly found 100% device functionality and no severe adverse events in any patient (pubmed.ncbi.nlm.nih.gov). The only findings were mild rotation of the sensor in two patients and stable pupil shape changes (observed in all) – neither caused vision loss (pubmed.ncbi.nlm.nih.gov). Crucially, no endophthalmitis, chronic inflammation, or glaucoma progression attributable to the device were seen even after years of use (pubmed.ncbi.nlm.nih.gov).

The data these implants provide are rich. In practice, patients use a handheld or wearable reader (or even a sleep mask with an embedded antenna) to activate and retrieve the IOP reading. For example, in a proof-of-concept, a patient tried a combination of an eyepatch (for daytime) and sleep-mask (for night) each with antenna coils, allowing 200+ readings per day (pmc.ncbi.nlm.nih.gov). The automated system measured IOP every 5 minutes continuously over 24 hours, capturing detailed curves. Such frequent sampling would be impossible in clinic, but with the implant it became “easy and well tolerated” overnight (pmc.ncbi.nlm.nih.gov). These automated systems deliver an unprecedented amount of information: it’s conceivable to obtain thousands of readings per year for a single patient, building a comprehensive 24-hour and seasonal IOP record.

An implant’s utility depends on efficient data management. Implandata’s clinical users now have access to a web-based dashboard where all IOP readings (and associated timestamps, positions) are charted (glaucomatoday.com). Clinicians can scroll through days of data, zoom in on suspicious peaks, and even overlay treatment logs. In many practices, physicians use these dashboards to make remote assessments. Some envision triggering layers of care: for example, if an implanted sensor records an unsafe morning spike, an automatic alert can prompt the doctor to call the patient in or adjust therapy.

Using Out-of-Office IOP Data in Management

24-hour (and multi-day) IOP profiles are not just academic—they change what we do for patients. Here’s how clinicians are using these new data:

• Revealing hidden pressure. Patients often have “normal” in-clinic IOP but substantial uncontrolled peaks at home. Continuous monitoring unearths these. In the Utah/JHU case series, home IOP monitoring “established pre-treatment IOP patterns that are not evident during in-clinic measurements,” including nocturnal peaks (pmc.ncbi.nlm.nih.gov). By revealing a patient’s true maximal IOP, doctors can re-classify risk. For example, a glaucoma suspect who peaks at 30 mmHg at 3 AM (missed in clinic) might be treated more aggressively than if judged by office IOP alone.

• Guiding medication adjustments. Once the full curve is known, therapy can be tailored. If the highest spikes occur at night, physicians often favor agents with strong nocturnal efficacy (e.g. prostaglandin analogs or evening dosing). Conversely, if daytime binding input is needed, beta-blockers or alpha-agonists might be timed differently. Rapid home feedback lets doctors accelerate medication changes. For instance, one series noted that in a normal-tension glaucoma trial 56% of patients had their treatment changed because home monitoring identified otherwise unseen spikes (www.ophthalmologymanagement.com). In pediatric glaucoma, 76% of eyes had medication regimens altered after self-tonometry revealed their true IOP swings (pmc.ncbi.nlm.nih.gov). In these cases, doctors used new drops, changed dosing times, or added oral therapy guided by the remote data.

• Timing and choice of surgery (MIGS/trab). A major impact of continuous IOP data is on surgical decision-making. In the same case series (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov), patients with persistently high home IOP despite medications underwent earlier glaucoma surgery (e.g. hydrus microstent plus phaco, or suprachoroidal shunt). The home graphs quickly showed that non-surgical methods weren’t controlling peaks, prompting surgical intervention. For example, a patient suffering nocturnal pressure surges despite multiple medications and a prior canaloplasty underwent PreserFlo implantation; afterwards, home tonometry confirmed relief of the early-morning spikes (pmc.ncbi.nlm.nih.gov). Another patient with optic nerve progression but stable clinic pressures underwent trabeculectomy based on home data; post-surgery his average home IOP dropped from ~15.5 to 9.2 mmHg and large peaks disappeared (pmc.ncbi.nlm.nih.gov). Essentially, doctors report that having out-of-office IOP accelerates surgery timing. Some patients who might have waited months before a decision are now offered MIGS or filtering surgery within weeks of detecting unacceptably high spikes.

  In fact, clinicians using iCare HOME have described actively “flattening the curve” through management (www.ophthalmologymanagement.com). In routine practice, doctors compare patients: one may undergo a trab or tube shunt when home monitoring shows persistent, high-amplitude curves; another may remain on drops if multiple-day curves are flat even with modest IOP. Wirostko reported seeing “IOPs flatten with no fluctuation” in patients who subsequently had shunts, whereas those with lesser interventions still showed variability (www.ophthalmologymanagement.com) (www.ophthalmologymanagement.com). Thus, continuous data help answer the question “Which procedure will truly control this patient’s IOP throughout the day?” by providing before-and-after curves.

• Remote monitoring and follow-up. Home tonometry also enables remote follow-up after interventions. For example, after selective laser trabeculoplasty (SLT), patients can take home tonometers to monitor effect. Studies show that reductions in mean IOP after SLT are detectable via patient self-tonometry (www.ophthalmologymanagement.com). Similarly, after a trabeculectomy or tube shunt, a patient can relay regular IOP logs remotely, allowing the surgeon to catch rises (bleb failure, tube occlusion) without an extra clinic visit. This is especially useful for patients in rural areas or with mobility issues. Clinics are even billing Medicare for this remote physiologic data under new RPM (remote patient monitoring) codes (www.ophthalmologymanagement.com).

Overall, early real-world evidence reflects that access to frequent home IOP readings changes clinician behavior. In one survey, 80% of glaucoma specialists agreed that home IOP data could improve management and help stratify risk. Nearly 60–80% of patients in clinical trials using home tonometers ended up with altered treatments (meds or procedures) after sharing their data (www.ophthalmologymanagement.com) (pmc.ncbi.nlm.nih.gov). In short, the availability of continuous pressure data is making glaucoma care more proactive and personalized.

Health Economics

From a health-system viewpoint, remote IOP monitoring appears promising. A recent systematic review found telemonitoring in glaucoma to be largely feasible and cost-effective, with participating studies reporting reduced patient travel and wait times and higher satisfaction (pmc.ncbi.nlm.nih.gov). These systems can help alleviate overburdened clinics by shifting routine checks into patients’ homes, akin to self-monitoring for diabetes or hypertension. In principle, early detection of uncontrolled pressures may prevent progression and avoid more costly late-stage blindness.

That said, long-term economic outcomes are still under study. The same review cautioned that we need more data on how telemonitoring affects costs, disease progression, and overall outcomes over years (pmc.ncbi.nlm.nih.gov). In practice, one obstacle has been device cost and reimbursement. For example, one pediatric study noted that although 84% of families and 80% of physicians believed home tonometry would help, only 14% of doctors actually lent patients devices, mainly due to financial constraints (pmc.ncbi.nlm.nih.gov). In the U.S., recent policy changes are addressing this: Medicare now offers reimbursement for remote monitoring of chronic eye conditions (via billing codes for analyzing patient-generated data and consulting on it) (www.ophthalmologymanagement.com). Clinicians report using these codes to offset the expense of staff time and device use in home IOP programs.

Ultimately, we expect the health-economic balance to tilt positive as home monitoring becomes routine. By enabling earlier interventions, it may reduce costs of disease progression. Machine-learning analyses on large telemetric IOP datasets may even predict which patients will progress, allowing preventive steps that save sight (and money). But large-scale studies or modeling will be needed to quantify these benefits definitively.

Patient Selection and Monitoring Protocols

Patient selection is critical. Not all glaucoma patients are ideal candidates. Good candidates include those with evidence of progression despite target IOPs in clinic, normotensive glaucoma patients with unexplained field loss, or those with high risk of fluctuation (e.g. sleep apnea). Also, performing home tonometry simultaneously with planned cataract or MIGS surgery can be efficient (since an implant or device can be placed during surgery). In contrast, very high-risk patients (apoptic angle closure, rapidly progressive VFD) are often monitored more closely in clinic; some specialists would hesitate to rely on home data alone for these individuals (pmc.ncbi.nlm.nih.gov). A UK survey of glaucoma specialists found no consensus on the “ideal” home-monitoring patient: many actually favored assigning it to lower-risk patients (to avoid missing acute events), while high-risk patients remained in close in-office follow-up (pmc.ncbi.nlm.nih.gov).

In practice, eligibility typically requires:

• Sufficient visual acuity, field, and manual dexterity to use the device reliably.
• Cognitive ability to follow instructions.
• Commitment to daily measurements (at least for a defined study period).
• Access to required technology (smartphone, internet, power) for data sync.

Monitoring protocols tend to follow clinical studies. For rebound tonometry, patients are often told: “measure your IOP 4–6 times per day at specific times (e.g. upon waking, mid-morning, afternoon, evening, and before sleep) for 7–14 consecutive days.” They may also measure upon any symptoms (e.g. headache) or when positional changes occur (sitting vs. lying). Devices like the iCare HOME2 log the time and laterality automatically. For implantable sensors, monitoring might involve once-daily readings (or specialized outfits like an antenna-equipped mask at night】9†L40-L49】.

Data review: Clinicians should establish how often they will check the data (e.g. weekly) and what they will do if they see problems. Many groups set up clinics or telehealth slots for reviewing home IOP reports. Some use dashboards with alert functions – for example, if a patient’s 2-week mean exceeds target by a set amount, a nurse may notify the physician. Others integrate the data into the electronic health record with flags, so any outlier automatically generates an in-basket message.

Training and support: A key to success is funding patient training and troubleshooting. One model is to train patients in-person on proper device use, and then have a tech team call the patient to ensure records are uploading correctly. Virtual training sessions (Zoom or video) can also help. In one report, home monitoring adherence improved when clinics provided patient ambassadors (experienced device users) for live chat coaching (www.ophthalmologymanagement.com). Ongoing support is crucial because even a well-chosen patient may need refresher tips (e.g. on positioning the tonometer or cleaning the contact lens sensor).

Conclusion

Emerging evidence indicates that 24-hour IOP monitoring is reshaping glaucoma care. Home rebound tonometry, contact-lens sensors, and implantable monitors together provide a continuous view of each patient’s eye pressure that was unimaginable a decade ago. These tools uncover hidden pressure peaks and patterns, directly informing therapy: physicians can escalate treatment or surgery sooner when warranted, or conversely gain confidence in keeping someone on observation if fluctuations are flat (pmc.ncbi.nlm.nih.gov) (www.ophthalmologymanagement.com). Health-economic analyses suggest telemonitoring is affordable and can reduce demand on busy clinics (pmc.ncbi.nlm.nih.gov).

As of 2025, pragmatic implementation is accelerating. Ophthalmologists should begin integrating home IOP data into their decision-making: identifying which patients need it most, training them on devices, and setting up data workflows. Organizations should prepare to analyze this influx of self-generated data, potentially with AI tools in the future. Just as diabetic patients now take charge of their glucose, glaucoma patients can become “active partners” in their care by tracking IOP at home (pmc.ncbi.nlm.nih.gov). In the near term, the main change will be cultural: recognizing that eye pressure is dynamic. In the longer term, continuous telemetry might even enable closed-loop drug delivery or smart implants. The revolution in glaucoma management is beginning – by embracing remote IOP monitoring, clinicians can deliver more precise, personalized care and ideally slow vision loss better than before.

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